1. Field of the Invention
The present invention relates to structural boards used for floors, and in particular, an improved tongue and groove board which can be assembled to form a floor surface.
2. Description of Related Art
Tongue and groove (T&G) structural boards are well known in the construction industry. They are typically made from plywood, particleboard, waferboard, strandboard, or other composite wood product materials. Tongue and groove boards are particularly well suited for installation on a joist framing assembly to form a structural sub-floor. T&G boards serve especially well as sub-flooring because of their interlocking edges which reduce vertical offset between adjacent boards resulting in a smoother floor. In addition, the interconnected edges prevent relative movement between adjacent edges as persons walk on the floor, thereby reducing squeaking in the floor. Typically, carpet, tile or a hardwood is installed over the structural sub-floor to provide the finished floor surface.
U.S. Pat. No. 4,807,416 to Parasin and U.S. Pat. No. 4,095,913 to Pettersson et al disclose tongue and groove boards incorporating particular tongue and groove shapes and features designed to reduce stresses generated by water absorption along the interconnected edges of adjacent T&G boards, and thereby reduce buckling. However, no provision is made for a means to reduce or prevent the accumulation of water on the upper surface of the sub-floor.
U.S. Pat. No. 2,031,596 to Fulbright discloses tongue and groove boards held together by an embedded spring to form a floor block assembly. U.S. Pat. No. 432,245 to Meigs discloses a lumber strip for installation over a sub-floor to form a finished floor surface which incorporates vertical channels spaced along the tongued edge of the strip. The channels are cut into the upper surface of the strip to accommodate blind nailing of the strip to the sub-floor.
U.S. Pat. Nos. 2,576,569 to Gemmer and 3,740,909 to Stinnes disclose wall boards incorporating interlocking grooves to provide a weathertight seal between adjacent boards.
While T&G boards are generally very useful in this application, they are subject to damage if water accumulates on the sub-floor surface during the construction of the building. Water often accumulates in small pools on the assembled sub-floor when rain or snow falls before the building is completed. The result is that the boards may buckle along their edges as the boards and the interlocking edges swell from water absorption. A solution for this problem is not disclosed on the prior art.
A need therefore exists for a T&G board for use in assembling a sub-floor assembly which reduces or prevents the accumulation of water on the upper surface of the sub-floor, and which is economical to produce without major modification to existing production facilities.